1. Technical Field of the Invention
The present invention relates to the cosmetic or pharmaceutical use of an extract of a nonfruiting (nonfructifying) nonphotosynthetic filamentous bacterium in a composition containing a cosmetically or pharmaceutically acceptable medium, as an agent increasing the endogenous synthesis of superoxide dismutase (SOD), in particular for preventing and/or limiting the formation of free radicals and/or removing the free radicals present in cells.
2. Description of the Prior Art
Over time, various signs appear on the skin which are very characteristic of aging, resulting in particular in a modification of the structure and functions of the skin.
This aging, which is of a physiological nature, results from the action of two main classes of components, an endogenous component resulting in particular from the natural production of superoxide ions, in particular produced during cell respiration. The other component is exogenous. Indeed, aging may be accelerated by environmental factors such as repeated exposure of the skin to sunlight, and in particular to ultraviolet A radiation, to pollution, in particular to diesel particles and to cigarette smoke.
It is known that the toxicity of atmospheric pollutants, in particular of gaseous pollutants such as sulphur dioxide, ozone and nitrogen oxides on the constituents of the skin (fibers, cells, enzymes) and on the sebum secreted by the skin is linked in particular to their free radical initiating activity, a source of oxidation phenomena which cause cellular damage in living beings.
Living cells, which are in direct and permanent contact with the external medium (in particular the skin, the scalp and certain mucous membranes) are particularly sensitive to these effects of gaseous pollutants, which result in particular in accelerated aging of the skin, with a complexion which lacks radiance and an early formation of wrinkles or fine lines, and also in a decrease in the vitality and a dull appearance of the hair.
It is also known that the irradiation phenomena caused by exposure to ultraviolet rays also lead to the phenomena of accelerated cellular aging.
Whether they are of endogenous or exogenous origin, free radicals cause substantial oxidative damage, in particular in the cell membranes (peroxidation of lipids causing a deterioration of the permeability of membranes), the cell nuclei (destruction of DNA) and the tissues, in particular the connective tissue (degradation of the elastin and collagen fibers, depolymerization of the polyuronic fibers). This damage leads in particular to drying and a loss of firmness and of elasticity of the skin (Grinwald et al., 1980, Agren et al., 1997).
Specialists currently consider that one of the causes of cellular aging is the reduction in the defense capabilities against free radicals and against oxidation phenomena (in particular the formation of superoxide ions) which they initiate.
The superoxide ion O°−2 (active oxygen) is a radical ion whose instability and reactivity make it a toxic compound, because it generates, in particular in the presence of metal ions, highly harmful hydroxyl free radicals (OH°). Superoxide dismutases (SOD) are enzymes which exert a protective effect in particular by trapping the superoxide ions and thus constitute a biological system of defence against the harmful effects of free radicals.
Superoxide dismutases are capable of inducing the dismutation of the superoxide ions, according to the reaction:2O°−2+2H+→H2O2+O2
Numerous superoxide dismutases are known. For example, superoxide dismutases extracted from bovine erythrocytes (Markovitz, J. Biol. Chem. 234, p. 40, 1959) and superoxide dismutases extracted from Escherichia coli (Keele and Fridovich, J. Biol. Chem., 245, p. 6176, 1970) have already been described. In the document FR-A-2,225,443 are described superoxide dismutases extracted from marine bacterial strains, and their method of preparation.
Superoxide dismutases make it possible in particular to protect the skin and the hair, in particular by maintaining the integrity of the natural keratin structure, as describes for example the document FR-A-2,287,899. In addition, superoxide dismutases improve cutaneous cell respiration and maintain or improve the qualities of the skin, such as softness to the touch, suppleness and elasticity.
Superoxide dismutases also protect the skin against the inflammation phenomena caused by ultraviolet radiation and against accelerated skin aging, in particular under the influence of such radiation.
Because of these advantageous properties, it is known to add superoxide dismutases to cosmetic compositions, in particular compositions intended for topical application (see, for example, EP-0-673,643 and EP-0-636,360).